Determination system for elasticity of volume of content of human brain cavity

摘要

The system comprises a probe used to insert a hollow body in the cavity to be tested. A unit measures the contents pressure. Across the inner opening of the probe, the cavity is cyclically filled then emptied with a determined volume of a medium. The pressure signal is measured some time after the filling and the signal stored as time series and after a time repeated. A digital auto correlation function is used on the content of the storage respectively with a correlator. With the correlator, from the measurement values gives a zero maximum (MaxO), a first maximum (Max1), a first minimum (Min1) and a time shift (DELTA t1). The largest possible multiple of the periods of the heart beat is computed and stored. The pressure signal is determined by a computer across a number of complete heart cycles. The average pressure signal is determined and the pressure alteration is formed as a difference from the average values. The volume elasticity is formed as a ratio of volume alteration to pressure alteration.